Power detector

An apparatus, comprising:

• a power amplifier;
• a power switch including a first terminal and a second terminal, wherein the power switch is coupled between the power amplifier and an antenna;
• a first squaring circuit including an input and an output, wherein the input of the first squaring circuit is coupled to the first terminal of the power switch;
• a second squaring circuit including an input and an output, wherein the input of the second squaring circuit is coupled to the second terminal of the power switch;
• a difference circuit coupled to the output of the first squaring circuit and the output of the second squaring circuit;
• and
• a low-noise amplifier coupled to the antenna.

An apparatus, comprising:

• a resistive element including a first terminal and a second terminal, wherein the resistive element is coupled between a power amplifier and an antenna;
• a multiplexer including a first input, a second input, and an output, wherein the first input of the multiplexer is coupled to the first terminal of the resistive element, and the second input of the multiplexer is coupled to the second terminal of the resistive element;
• a squaring circuit including an input and an output, wherein the input of the squaring circuit is coupled to the output of the multiplexer;
• a low pass filter including an input and an output, wherein the input of the low pass filter is coupled to the output of the squaring circuit;
• an analog-to-digital converter (ADC) including an input and an output, wherein the input of the ADC is coupled to the output of the low pass filter;
• and
• a difference circuit coupled to the output of the ADC.

A method for measuring power using a resistive element coupled between a power amplifier and an antenna, the method comprising:

• squaring a voltage from a first terminal of the resistive element to obtain a first signal;
• squaring a voltage from a second terminal of the resistive element to obtain a second signal;
• and
• generating a measurement signal based on a difference between the first signal and the second signal.